Tungsten Alloy W70Cu30-INF (Copper-infiltrated)
Heat-treated state · default condition
also CuW70
Standard commercial condition for EDM electrodes, switchgear contacts and heat spreaders — highest density and conductivity for a given W content.
Values for the INF condition
Other W70Cu30 tempers and conditions
W70Cu30 is listed in 3 conditions; see the grade overview at W70Cu30.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Mixed-powder press & liquid-phase sintered | Lower-cost route for simple contact shapes; slightly lower density and conductivity because of residual closed porosity. | 400 | 550 | 3 | 175 HB | 38 % IACS |
INFDefaultThis page Copper-infiltrated | Standard commercial condition for EDM electrodes, switchgear contacts and heat spreaders — highest density and conductivity for a given W content. | — | 620 | 5 | 185 HB | 42 % IACS |
HIP/vacuum-degassed high-density electronic grade | Choose for microwave packages, vacuum interrupters and hermetic heat sinks where closed porosity, outgassing and plating quality matter. | — | 660 | 6 | 190 HB | 45 % IACS |
What is W70Cu30-INF?
W70Cu30-INF is W70Cu30 heat treated to INF — standard commercial condition for EDM electrodes, switchgear contacts and heat spreaders — highest density and conductivity for a given W content. W70Cu30-INF has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 100% of tungsten alloy grades. Elongation at break is 5% and the elastic modulus is 230 GPa (33.4 Msi). W70Cu30-INF has a density of 14 g/cm³ (0.506 lb/in³), lighter than 100% of tungsten alloy grades. It melts at 1,083°C (1,981 °F).
Advantages
- Lightweight — 14 g/cm³ (0.506 lb/in³), better than 100% of tungsten alloy grades
- Conducts heat well — 200 W/m·K (115.6 BTU/hr·ft·°F), better than 100% of tungsten alloy grades
- High electrical conductivity — 42 % IACS, better than 100% of tungsten alloy grades
- Easy to machine — 35/100, better than 90% of tungsten alloy grades
- Low embodied carbon — 19 kg CO₂/kg, better than 90% of tungsten alloy grades
Limitations
- Low strength — 450 MPa (65.3 ksi), worse than 100% of tungsten alloy grades
- Low stiffness — 230 GPa (33.4 Msi), worse than 100% of tungsten alloy grades
W70Cu30-INF properties
Typical room-temperature values for W70Cu30-INF; 10 are specific to this condition. Other listed values are W70Cu30 reference data and may not represent this condition. Bars are the position among tungsten alloy grades.
Physical2
W70Cu30-INF has a density of 14 g/cm³ (0.506 lb/in³), lighter than 100% of tungsten alloy grades. It melts at 1,083°C (1,981 °F).
Mechanical13
W70Cu30-INF has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 100% of tungsten alloy grades. Elongation at break is 5% and the elastic modulus is 230 GPa (33.4 Msi).
Thermal5
W70Cu30-INF is rated for continuous service to 600°C (1,112 °F). It conducts heat at 200 W/m·K (115.6 BTU/hr·ft·°F), better than 100% of tungsten alloy grades. Thermal expansion is 9.4 µm/m·K (5.22 µin/in·°F).
Electrical3
W70Cu30-INF conducts electricity at 42 % IACS, better than 100% of tungsten alloy grades.
Chemical & Environmental3
Corrosion resistance is fair (50/100), worse than 69% of tungsten alloy grades.
Sustainability4
Producing a kilogram of W70Cu30-INF takes about 300 MJ of energy and emits 19 kg of CO₂ — less than 88% of tungsten alloy grades. Typical recycled content is 25%.
Manufacturability7
W70Cu30-INF's machinability is fair (35/100, better than 90% of tungsten alloy grades); weldability poor (15/100); formability not recommended (5/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with W70Cu30-INF
Is W70Cu30 easy to machine?
Turn/mill with sharp micrograin-carbide or CBN tooling, light feeds, flood coolant and rigid setups; wire- and sinker-EDM, surface grinding and lapping are the preferred finishing routes.
Can W70Cu30 be welded?
Not fusion weldable — join by silver brazing (BAg-series) or Cu/Ag interlayer diffusion bonding to copper shanks and steel holders; keep braze cycles below ~900 °C to avoid copper sweat-out.
Can W70Cu30 be formed, bent or molded?
No cold or hot forming; net shape comes from powder pressing/infiltration plus machining, with sintered blanks in plate, rod, bar and custom preform forms.
What surface finishes work on W70Cu30?
Electroless/electrolytic Ni (2–5 µm) followed by Au or Ag plating for solderability and oxidation resistance; degas and bake before plating to avoid blistering from residual porosity.
W70Cu30 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Wtungsten skeleton, 68–72 wt% typical trade tolerance ±2 % | 68 – 72 | 70 |
| Nioptional sintering activator in press-sintered variants only | 0 – 0.5 | — |
| Other impurities (Fe, Mo, C, O)total, per GB/T 8320 / producer specs | ≤ 0.5 | — |
| Cuinfiltrant / matrix | ≥ 28 (balance) | — |
W70Cu30-INF — frequently asked
What is W70Cu30-INF used for?
W70Cu30-INF is typically used for EDM electrodes, high-voltage switch contacts, heat sinks and resistance welding electrodes. In short: best-conducting W-Cu grade; workhorse EDM electrode; balanced erosion and conductivity.
What is the yield strength of W70Cu30-INF?
W70Cu30-INF has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 100% of tungsten alloy grades. Strength varies by condition: see the 3 listed tempers.
Is W70Cu30-INF easy to machine?
Not especially — machinability is rated fair (35/100, better than 90% of tungsten alloy grades). Turn/mill with sharp micrograin-carbide or CBN tooling, light feeds, flood coolant and rigid setups; wire- and sinker-EDM, surface grinding and lapping are the preferred finishing routes.
Can W70Cu30-INF be welded?
Not readily — weldability is rated poor (15/100). Not fusion weldable — join by silver brazing (BAg-series) or Cu/Ag interlayer diffusion bonding to copper shanks and steel holders; keep braze cycles below ~900 °C to avoid copper sweat-out.
What surface finishes work on W70Cu30-INF?
Electroless/electrolytic Ni (2–5 µm) followed by Au or Ag plating for solderability and oxidation resistance; degas and bake before plating to avoid blistering from residual porosity.
Can W70Cu30-INF be formed, bent or molded?
No cold or hot forming; net shape comes from powder pressing/infiltration plus machining, with sintered blanks in plate, rod, bar and custom preform forms.
What is the maximum service temperature of W70Cu30-INF?
W70Cu30-INF is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between W70Cu30-INF and W70Cu30-PS?
INF is the default condition — standard commercial condition for EDM electrodes, switchgear contacts and heat spreaders — highest density and conductivity for a given W content. PS: lower-cost route for simple contact shapes; slightly lower density and conductivity because of residual closed porosity. Yield strength is 450 MPa in INF versus 400 MPa in PS.
Sources
- ASTM B702 Standard Specification for Copper-Tungsten Electrical Contact Material — ASTM (2017)
- ASM Handbook Vol. 7: Powder Metallurgy (infiltrated W-Cu composites) — ASM International (2015)
- ASM Handbook Vol. 2: Properties and Selection — Refractory Metals and Alloys — ASM International (1990)
- Tungsten-copper WCu70/30 material data — Plansee / Mi-Tech Tungsten Metals (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.